is the difference? Is it just that a tuber may be shaped different than a
bulb?

Bulbs are made up of layers or scales. Good example, an onion.

Tuber is probably most appropriate, being defined as "A short, thick,
usually, but not always subterranean stem or branch bearing buds or 'eyes'
and serving as a storage organ, as in the potato..." (Hortus III)

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From: Lester Kallus lkallus at earthlink.net> on 2003.05.06 at 09:16:17(10189)We all know onions so there's the great example of bulbs and we all know potatos so we know tubers. I grow Canna so understand rhizomes but have never thought of an edible example of thizomes. More importantly, though, is there an edible corm?

Les Kallus

From: "Patricia Frank" tricia_frank at hotmail.com> on 2003.05.07 at 06:00:56(10200)Ginger

We all know onions so there's the great example of bulbs and we all know
potatos so we know tubers. I grow Canna so understand rhizomes but have
never thought of an edible example of thizomes. More importantly, though,
is there an edible corm?

Les Kallus

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From: Jonathan Ertelt jonathan.ertelt at vanderbilt.edu> on 2003.05.07 at 07:50:32(10202)>>What is a corm?
>
>Again according to Hortus III, a corm is "a solid, swollen part of a
>stem, usually subterranean, as the so-called "bulb" of Crocus and
>Gladiolus".
>
>Think of it this way:
>
>A tuber is a modified root
>A corm is a modified stem
>A bulb is a modified leaf bud.
>

You could think of it this way, but according to several of my botany
texts, this is not correct. Both tubers and corms are modified stems, (as
is a rhizome,btw). A potato is indeed a tuber, a modified stem, while a
sweet potato is botanically referred to as a tuberous root, because it is
tuber-like, but being a root, it is not a tuber.

Several years back there was some extended discussion on this listserve
whether or not we were talking about tubers or corms when we were
discussing both Amorphophallus and Arisaema. (It may be that bulb came up
as a possibility also, but that is so obviously incorrect that I don't
really recall.) The consensus wound up favoring tuber as the correct term,
though I was never thoroughly convinced, nor did I get into the discussion
much. At any rate, both these structures, i.e. tubers and corms, are
modified stems.

From: Jonathan Ertelt jonathan.ertelt at vanderbilt.edu> on 2003.05.07 at 07:55:38(10203)>We all know onions so there's the great example of bulbs and we all know
>potatos so we know tubers. I grow Canna so understand rhizomes but have
>never thought of an edible example of thizomes. More importantly, though,
>is there an edible corm?

Les,

Though often mis-labeled, the ginger "root," (even Jeopardy got his wrong
with a final Jeopardy question about root crops a couple of years back, to
which the correct response for their answer was "What is ginger?") is
probably the most commonly consumed edible rhizome. I suspect that
Arrowroot is also a rhizome product (I'm blanking on the name I'm looking
for here, though I think it is most commonly used more as a thickening
agent than as a dish or a flavoring.

From: "Michael Marcotrigiano" mmarcotr at email.smith.edu> on 2003.05.07 at 09:13:24(10204)I haven't read all the strings of email but I still think konjac is a
corm and it is edible. I've dug up konjacs in the leaf expansion stage
and like a typical corm, the corm is 'absorbed' and a new one forms on
top with roots pulling it in deeper as the season progresses. Are there
still believers that konjac is a tuber?

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From: Robb Smith resmith at saltspring.com> on 2003.05.07 at 10:55:34(10207)The corms of a number of gladioli are edible. I have a species named Gladiolus
edulis, in fact. The roasted corms are supposed to taste like chestnuts.
Gladiolus spicatus corms are also edible.

From: Iza & Carol Goroff goroff at idcnet.com> on 2003.05.08 at 10:01:42(10216)I think the appropriate way to distinguish between "tuber" and "corm" is that
a tuber is a modified rhizome (a horizontal underground stem) and a corm is a
modified vertical stem. A tuber may produce roots or buds at any point on its
surface whereas a corm retains an approximate cylindrical symmetry (except
when splitting) with a cental bud and with roots produced at the edge of a
circle, usually at its base. I think the so-called "consensus" was incorrect.

> Several years back there was some extended discussion on this listserve
> whether or not we were talking about tubers or corms when we were
> discussing both Amorphophallus and Arisaema. (It may be that bulb came up
> as a possibility also, but that is so obviously incorrect that I don't
> really recall.) The consensus wound up favoring tuber as the correct term,
> though I was never thoroughly convinced, nor did I get into the discussion
> much. At any rate, both these structures, i.e. tubers and corms, are
> modified stems.